Signal Transmission Quality Research Articles

GAO–FCNN–Enabled Beamforming of the RIS–Assisted Intelligent Communication System

The joint beamforming optimization from the perspective of the bit error rate (BER) in a reconfigurable intelligent surface (RIS)–assisted intelligent communication system is studied in this paper. A genetic algorithm (GA) is investigated to address the bottleneck of the system performance based on the dynamic adaptability theory. However, the bottleneck is caused by the interaction between the active and passive beamforming. To tackle the constraints of conventional optimization approaches, the hybrid scheme is proposed to combine the GA optimization (GAO) and fully connected neural network (FCNN) strategy. Specifically, the intelligent collaborative tuning of system parameters is achieved using this proposed technique. Simulation findings indicate that the hybrid scheme not only simplifies the calculation process to obtain the optimal network parameters, but also effectively optimizes the system structure by dynamically adjusting the RIS reflection configuration. Based on this, the signal transmission quality is improved, interference is reduced, and the stable and efficient operation of the RIS–assisted intelligent communication system is ensured in the complex wireless transmission scenario.

Durable Superhydrophobic Coatings with Attapulgite for Inhibiting 5G Radome Rain Attenuation.

5G radomes are easily wetted and stained by rainfall, which greatly reduces the quality of signal transmission. Superhydrophobic coatings are expected to solve this problem because of their unique wettability, but it is still challenging to develop robust superhydrophobic coatings via simple methods. Here, we report the design of robust superhydrophobic coatings containing oxalic acid-modified attapulgite (MDP) for inhibiting rain attenuation of 5G radomes. First, a homogeneous suspension was prepared by nonsolvent-induced phase separation of a silicone-modified polyester adhesive (SMPA) solution containing fluorinated MDP (F-MDP) nanorods. Superhydrophobic coatings can be easily prepared by spraying the suspension. The effects of phase separation and the SMPA/F-MDP ratio on the surface morphology, superhydrophobicity, and stability of the coatings were systematically investigated. The micro-/nanostructure and low surface energy endow the coatings with excellent static and dynamic superhydrophobicity. Compared with previous studies, the coatings exhibit excellent mechanical stability, flexibility, chemical stability, and pressure resistance due to the combined effects of adhesion by SMPA, self-similar micro-/nanostructures, reinforcement by the MDP nanorods, etc. Consequently, the coatings show good performance in preventing rain attenuation of 5G radomes, an emerging application of Superhydrophobic coatings. We believe that the coatings have great application potential in various fields, including 5G communication.

Research on high-speed digital optical signal jitter measurement technology based on clock recovery algorithm using eye diagram opening area

With the rapid development of information technology, high-speed digital optical signal transmission technology has become the core of modern communication networks. However, the increase in transmission rates brings challenges such as noise, distortion, and interference, which affect the accuracy of clock recovery. To address these issues, this study proposes a clock recovery algorithm based on the eye diagram opening area to improve the accuracy and efficiency of high-speed digital optical signal jitter measurement. The proposed method extracts clock information from the signal using the opening area and curvature characteristics of the eye diagram for jitter measurement. Experimental results demonstrate that the clock recovery algorithm based on the eye diagram opening area can stably reconstruct the signal eye diagram and obtain jitter parameters under different optical power conditions. At optical powers of −7.2 dBm, −12.2 dBm, and −17.2 dBm, the Q-factors were 8.8, 7.6, and 4.3, respectively, and the RMS jitter values were 12.2 ps, 13.4 ps, and 21.2 ps, respectively. At optical powers of −2.3 dBm, 0.1 dBm, 2.4 dBm, 4.6 dBm, and 6.0 dBm, the Q-factors were 9.1, 9.3, 9.5, 9.7, and 10.0, respectively, and the average jitter values were 8.9 ps, 8.5 ps, 8.0 ps, 7.5 ps, and 7.0 ps. These results indicate that the proposed algorithm performs excellently under low optical power conditions and maintains high recovery accuracy even when jitter increases at higher optical powers. The clock recovery algorithm based on the eye diagram opening area significantly improves the accuracy and stability of high-speed digital optical signal jitter measurement, enriches the theoretical research of clock recovery algorithms, and shows significant advantages in improving signal transmission quality, reducing bit error rate, and enhancing communication link reliability. The research outcomes provide key technical support for the optimization of modern high-speed optical communication systems.

Path optimization algorithm for mobile sink in wireless sensor network

In order to alleviate the limitation of mobile sink in Wireless Sensor Network (WSN) by environmental and power problems, this paper proposes a new signal collection method for network communication in wireless sensor network with the goal of shortening the path of the mobile sink, and then proposes the ACO-TU (Ant Colony Optimization-Team Up) algorithm based on ant colony algorithm by adding concepts such as node pheromone. The algorithm groups the mobile units of the ant colony algorithm and further optimizes the sink path in the wireless sensor network by specific mobile strategies. Experimental results show that the method of sink moving path optimization proposed has a significant improvement in reducing power consumption and distance shortening, which can further increase the service life of the mobile sink and improve the quality of signal transmission. The results of comparison with the most recent relevant algorithms show that the ACO-TU algorithm has the best optimization performance, which proves the effectiveness of the algorithm.

High-Speed 2x1 Multiplexer with Carrier-Reservoir Semiconductor Optical Amplifiers

Leveraging the rapid carrier recovery times and minimal polarization sensitivity of carrier-reservoir semiconductor optical amplifiers (CR-SOAs), this study embeds them in a Mach–Zehnder interferometer (MZI) setup to emulate a 2x1 multiplexer (MUX) operating at 120 Gb/s. The focus is on incorporating AND logic gate functionalities into the CR-SOAs-based MZI structure to facilitate high-quality multiplexing. The proposed methodology utilizes the intrinsic gain and phase modulation capabilities of CR-SOAs-based MZI to effectively manipulate data streams. This innovative approach capitalizes on the unique properties of CR-SOAs, such as fast response times and low polarization sensitivity, to achieve optimal signal transmission quality and efficient multiplexing. To assess MUX performance, a quality factor metric is introduced as a comprehensive measure of signal integrity. Through exhaustive simulations and meticulous analysis, the study demonstrates the feasibility of achieving the desired data rate while maintaining superior signal transmission quality. The results underscore the efficacy of CR-SOAs-based MZI as versatile modules for high-speed multiplexing applications, offering unparalleled performance and efficiency. This research represents a significant advancement in understanding optical communication systems and provides valuable insights for optimizing signal quality and mitigating interference in practical real-world scenarios.

Improving Signal Transmission Quality of Wind Turbine Pitch Slip Ring With Copper Matrix Composites

Abstract To improve the signal transmission quality, copper matrix composites added with different contents of carbon nanotubes (CNTs) and molybdenum disulfide (MoS2) were prepared. The electrical and tribological properties of composites were studied. A new parameter, the correlation dimension of electrical noise, was proposed to quantitatively characterize the stability of signal transmission. Copper matrix composites added with reasonable amount of CNTs and MoS2 can effectively reduce the values and fluctuations of friction coefficient and improve the wear resistance, efficiency, and stability of the signal transmission. Tribo-films are generated on the surface of composites. The contents of CNTs and MoS2 affect the stability of tribo-film and further affect the signal transmission quality. 0.5 wt% CNTs and 15 wt% MoS2 can make good synergistic effects on improving the signal transmission quality of composites. The results provide good guidance to improve the signal transmission quality of wind pitch slip rings.

Tunable Negative and Positive Photoconductance in Van Der Waals Heterostructure for Image Preprocessing.

The processing of visual information occurs mainly in the retina, and the retinal preprocessing function greatly improves the transmission quality and efficiency of visual information. The artificial retina system provides a promising path to efficient image processing. Here, graphene/InSe/h-BN heterogeneous structure is proposed, which exhibits negative and positive photoconductance (NPC and PPC) effects by altering the strength of a single wavelength laser. Moreover, a modified theoretical model is presented based on the power-dependent photoconductivity effect of laser: , which can reveal the internal physical mechanism of negative/positive photoconductance effects. The present 2D structure design allows the field effect transistor (FET) to exhibit excellent photoelectric performance (RNPC=1.1× 104AW-1, RPPC=13AW-1) and performance stability. Especially, the retinal pretreatment process is successfully simulated based on the negative and positive photoconductive effects. Moreover, the pulse signal input improves the device responsivity by 167%, and the transmission quality and efficiency of the visual signal can also be enhanced. This work provides a new design idea and direction for the construction of artificial vision, and lay a foundation for the integration of the next generation of optoelectronicdevices.

Real-Time UAV Trajectory Prediction for UTM Surveillance Using Machine Learning

The Unmanned Aerial System (UAS) Traffic Management (UTM) surveillance plays an important role in monitoring the safety compliance of UAV flights within specific operational zones. However, the quality of data reception from UAVs depends on transmission signal quality, leading to variable data latency during flights. As a means of addressing this issue and improving UAV operational safety, trajectory prediction emerges as a promising solution. This study aims to implement real-time trajectory prediction through the integration of machine learning techniques within the UTM surveillance system using Broadcast Remote ID. To facilitate this, a homemade receiver for broadcast Remote ID is developed using the ESP32 microcontroller. Subsequently, two distinctive flight tests are executed using a DJI Phantom 4 UAV. In the first flight, UAV trajectory data are used to serve as training input for the machine learning algorithms. The second flight focuses on the implementation of real-time trajectory prediction. The trajectory prediction model uses inputs such as latitude, longitude, height, speed, direction, latency time, and the Received Signal Strength Indicator (RSSI). Through an analysis of the first flight’s offline data, the Gated Recurrent Unit (GRU) algorithm is preferred to the Long Short-Term Memory (LSTM) algorithm. The outcomes of the second flight test prove the feasibility of the GRU-based trajectory prediction. The GRU model successfully produces real-time predictions during UAV flight, showcasing accuracy levels similar to those derived from offline prediction analyses with short processing time. This real-time trajectory prediction could improve the safety of UAV operation by providing the estimated position when the latency time is higher than the threshold.

Increasing the accuracy of signal formation by changing the sampling rate

The problem of changes in the audio signal when changing the sampling frequency arose a long time ago, but interest in it has recently become more acute with an increase in the quality of signal formation and transmission. To some extent, this was also determined by the methods of assessing the quality of changes in the harmonic signal without taking into account changes in the actual broadcast signal. Algorithms for the formation of a new digital sequence after changing the sampling rate provided perfect quality in the conversion of the sinusoidal signal and large errors in the conversion of the real signal. Algorithms for changing the sampling rate Fd have been improved. The aim of this work is to study the features of changes in the sampling frequency in the paths of the broadcast channel and to develop algorithms for converting the sampling frequency in the frequency domain with an increase in conversion accuracy. It is shown that the algorithms for converting the sampling rate in the time domain have reached perfection and cannot be improved, so the transition to processing in the frequency domain is important. An algorithm for converting the sampling frequency in the frequency domain has been developed. The spectrum of the error signal for various types of converters is determined and the need for its compensation is determined. A method for introducing predistortions for converters with known and unknown sequence of sample rates used has been developed. The use of the results of this work makes it possible to improve the quality of broadcasting signals and information programs.

Vibration sensor as the basis of an equipment monitoring system

Currently, the high complexity and instability of engineering production processes leads to the need to make management decisions under conditions of uncertainty, which significantly affects the efficiency of production as a whole. Reducing uncertainty in operational production planning of machine-building industries is possible by analyzing data on the flow of technological processes collected using equipment monitoring systems, i.e. measuring and information systems. It is proposed to use vibration sensors as the main source of information to obtain reliable data on the operation of equipment. General issues regarding vibration sensors are considered and a variant of their classification according to various features is presented, such as sensitivity, operating principle, method of obtaining information, signal conversion mechanism, signal measurement method. Several versions of vibration sensors have been developed, designed to collect information about the level of vibration during processing and included in the diagnostic module for monitoring equipment operation. The first version of the printed circuit board is based on a microcontroller based on ATMega328P, designed to read MEMS accelerometer data and transmit the collected information using a wireless communication module to the operator panel for display in real time and transmission for storage and processing to the server. To charge the battery, a charge controller based on the TP4056 chip and a low-dropout linear stabilizer TPS730 are used. In the second option, the MPU9250 inertial measurement module is used, and information processing and data transmission is carried out using a specialized module NINA-B306. A printed circuit board of any of the presented options is installed in a vibration control sensor mounted on the back side of a three-jaw chuck inside the machine body. This placement of the diagnostic module eliminates the possibility of its unintentional damage while ensuring the required quality and reliability of signal transmission. The vibration sensor, fixed to the cartridge using quick-release strips, consists of a board located in the housing. Above the board there is an insert that protects the board from the battery. The housing is closed from above with a lid using screw washers through a gasket to ensure the housing is sealed. The clamping screw is used to secure the board in the case. The vibration sensor is turned on using a button. The proposed vibration sensor can be used as the basis of an measuring and information systems, because information about the level of vibration of a technological system, recorded by sensors, like a human cardiogram, provides comprehensive information about its condition. A diagnostic module built on the basis of a vibration sensor will increase the efficiency and “transparency” of machining processes and collect statistical data that allows assessing the efficiency of equipment operation.

Effects of some weather variables on the signal strength of Maloney FM radio, Nasarawa State, Nigeria

This study aims to assess the effects of atmospheric temperature, relative humidity, and atmospheric pressure on the signal strength of Maloney FM Radio, 95.9 MHz, Keffi, Nasarawa State. It is essential to measure the signal strength of the new radio station in relation with some parameters of weather to provide effective service delivery to the critical sectors and the entire populace. The research was conducted using the data of atmospheric temperature, atmospheric pressure, relative humidity, and the strength of the Maloney radio signal acquired from 6.00 a.m. to 6.00 p.m. daily at a 30 min interval, from January 2023 to June 2023, in Karshi, Abuja, a neighbouring town to Nasarawa state where the radio station is located. The data analysis involving cointegration and descriptive statistics of the effects of atmospheric variables on the radio signal strength was implemented using Eviews and Microsoft Excel Software. The results showed daily and monthly variations of the radio signal strength as well as the atmospheric temperature, atmospheric pressure and relative humidity. The variation is such that the lowest monthly signal strength was in June, probably due to higher rainfall in the area in June being the last month in this work (Jan.–Jun.) compared to other months which are dry season (January–March) or when the rain was just starting (April–May), in the study area. It was observed that atmospheric temperature and pressure negatively correlate with signal strength while relative humidity positively correlates with received signal strength in all the six months under study. The cointegration analysis also showed a long-term relationship between the radio signal strength and the atmospheric components, as the probability on the first row on the tables of both Trace Test and Maximum Eigenvalue methods were 0.0016 and 0.0008, which are less than the 5% (0.05) set critical value. In the same way, the critical value results on the same first row in both methods are smaller than the Trace statistics values. This implies that there is a long-term relationship between the atmospheric variables and the Maloney FM radio signal strength. These results will help mitigate the attenuation effect, and attendant signal loss of the radio station's signal strength. By proxy, the results will support the operations and regulations of spectrum management in the design of satellite communications and satellite microwave band specifications in Nigeria. In addition, the pre-determination of the radio station location will depend on this study's result analyses, considering that the effects of atmospheric temperature, pressure, and humidity conditions are inevitable. Governments, policymakers, stakeholders, and other relevant authorities should ensure the domestication of the study by providing the necessary research materials and facilities for wider studies. As regards the Maloney FM radio station, Keffi, studied in this work, there is no similar or related work done on it before now, hence, providing the detailed relationship between the signal strength of the radio station and some weather variables will go a long way in the improvement of the quality of signal transmission from Maloney radio station. The results when provided to the station, will enable the management to also evaluate if their set target of the station such as the radio horizon, radio signal coverage, and the link budget have been met.

Adaptive simulation of digital signal transmission

High-order modulated signals have lower anti-interference ability than low-order modulated signals with the same modulation method and conditions. In situations with low signal-to-noise ratios, the quality of high-order signals can degrade significantly. An algorithm capable of intelligently switching the modulation order based on the current signal-to-noise ratio can effectively address this issue. This paper presents an adaptive signal transmission algorithm that intelligently selects different orders of Phase shift keying (PSK) modulation depending on varying signal noise ratio (SNR) conditions, while ensuring the user-specified upper limit of bit error rate (BER). This approach guarantees signal transmission quality. The algorithm is implemented in Python and involves simulating the relationship curve between SNR and BER for different PSK orders. This simulation is combined with theoretical transmission rate analysis, resulting in an adaptive algorithm that intelligently switches modulation methods under complex conditions to meet transmission requirements. The proposed algorithm dynamically adapts to diverse user requirements for signal-to-noise ratios in various environments. It achieves this by adjusting the modulation order, calculating theoretical transmission times based on the given signal frequency, and ultimately verifying the actual bit error rate through transmission and testing. Upon testing, this design successfully achieved its intended goals.

Three‐dimensional geometry‐based channel modeling and simulations for reconfigurable intelligent surface‐assisted uav‐to‐ground MIMO communications

AbstractConsisting of a large number of passive reflectors, reconfigurable intelligent surface (RIS) has gained traction as an approach to enhance communication quality. The specular reflection assumption is common when ideal conditions are considered. In this paper, an anomalous‐reflector model was found for each RIS reflection unit, deviating from the specular reflector assumption, and the impacts of the aperture area and radiation pattern of the RIS reflecting elements are taken into account. A three‐dimensional (3D) geometry‐based RIS‐assisted channel model is proposed for stochastic multiple‐input multiple‐output (MIMO) unmanned aerial vehicle (UAV)‐to‐ground communications. The RIS is deployed on an additional UAV in the proposed model, which assists the UAV transmitter for reflecting its own signals to the mobile receiver (MR) on the ground level, thereby boosting the quality of signal transmission. In order to achieve a perfect beam alignment towards the desired direction, the reflection phase is regulated by considering the propagation distances among UAV, RIS, and MR.

Research on developing an adaptive algorithm for enhancing the quality of underwater positioning based on the sonar USBL principle

The paper proposes an enhanced solution for improving the accuracy of underwater object positioning based on the Ultra-Short Baseline (USBL) sonar principle. In shallow water regions, complex hydrological phenomena affect the quality of underwater acoustic signal transmission and reception, making it essential to enhance the processing of these signal groups. Through the USBL system model, the paper presents a model capable of adaptively selecting accurate signals amidst the noisy underwater environment. The proposed model is implemented and validated in practice using FPGA hardware in Lan Ha Bay. The results demonstrate the effectiveness of the proposed algorithm compared to conventional approaches, as it extends the management range and optimizes the transmission power of the system, even in cases of low signal-to-noise ratio.

Audio signal transmission method in network-based audio analytics system

The subject matter of the article is аudio signal transmission method in network-based audio analytics system. The creation of a network-based audio analytics system leads to the emergence of new classes of load sources that transmit packetized sound data. Therefore, without constructing adequate mathematical models, it is impossible to build a well-functioning network-based audio analytics system. A fundamental question in traffic theory is the question of load source models. The development of an method for transmitting audio signals in a network-based audio analytics system becomes necessary. Based on this, the goal of the work is to create methods an method for transmitting audio signals in a network-based audio analytics system to ensure efficiency and accuracy in audio analytics. The following tasks were solved in the article: the formation of a model for the system's load sources, investigation of connection and traffic management, implementation of control and traffic monitoring functions in the network, research of methods to ensure the quality of audio signal transmission and the development of a method of transmitting an audio signal by virtual routes switching. To achieve these goals, the following methods are used: mathematical signal processing, data compression algorithms, optimization of network protocols, and the use of high-speed network connections. The obtained results include modeling of the system's load sources, examination of connection and traffic management, investigation of methods to ensure the quality of audio signal transmission and a method of transmitting an audio signal by virtual routes switching was proposed. In conclusion, the possibilities of using simulation modeling of nodes in the network-based audio analytics system are highly limited. This is explained by the fact that the acceptable level of information loss in data centers is very low. The use of the developed method enables effective control and processing of sound information in real-time. This method can find broad applications in various fields, including security, healthcare, management systems, and other industries where the analysis of audio signals is a crucial element.

Автоматизированное проектирование расположения базовых станций беспроводной сотовой связи

The planning of wireless base stations is a multi-purpose task of optimizing combinations, and the main goals of optimization include cost reduction, increased coverage and quality preservation. The paper pays attention to the consideration of the coverage radius, the quality of signal transmission and two types of signal interference. To implement the tasks set for the location of the base station, the following algorithms were used: PMET-PSO and PPSO-GA, which became the basis for the module for solving problems of designing the location of base stations in the proposed automated design system. Using the C/S architecture and 3D CAD based on ACIS and Google Earth, based on an in-depth analysis of the actual requirements for the base station, a CAD for the location of wireless cellular base stations is proposed. The main technical modules of the system are the technology of rapid modeling involving objects in the planning of base stations, the technology of multi-purpose modeling and solving problems of planning base stations and the technology of distributed joint integration of program modules. The technology for solving planning problems uses the PMET-PSO and PPSO-GA algorithms. Both algorithms compensate for the disadvantages of their original algorithms (MET-PSO and PSO-GA) and retain their respective advantages: time - PMET-PSO, and if the user does not care about time and wants to get the optimal possible solution, then the PPSO-GA algorithm. Both algorithms combine memory computing with good parallelism, which plays a crucial role in solving multi-purpose optimization problems.

Multi-Domain Resource Multiplexing Based Secure Transmission for Satellite-Assisted IoT: AO-SCA Approach

Due to the wireless broadcasting and broad coverage in satellite-supported Internet of things (IoT) networks, the IoT nodes are susceptible to eavesdropping threats. Considering the distance difference between satellite and nearby destinations is negligible, the main and wiretapping channels between satellite and IoT node are similar, it poses great challenges to reach physical layer security in satellite-assisted IoT networks. In this paper, to guarantee secure transmissions for satellite-assisted IoT downlink communications, the multi-domain resource multiplexing based secure approach is proposed. Particularly, the self-induced co-channel interference between adjacent nodes is leveraged to increase the difference of signal transmission quality over both main and wiretapping channels. By comprehensively optimizing multi-domain resources, i.e., frequency, power, and spatial domains, secure transmissions from satellite to IoT nodes are reached. Specifically, the problem to maximize the sum secrecy rate of IoT nodes is formulated with a constraint of common communication rate of IoT nodes. To solve this non-convex problem, an alternating optimization (AO) algorithm with two inner successive convex approximation (SCA) algorithms are executed to solve the power allocation, spectral multiplexing, and precoding. In addition, simulation results are carried out to evaluate the secrecy rate performance and verify the efficiency of our proposed approach.

FPGA-based pulsed laser with high modulation depth from Mach-Zehnder electro-optic modulator and its application

Mach-Zehnder electro-optic modulator as the essential component of high-speed modulation in the optical fiber communication and sensing system, its stability control of operating bias-point plays a key role in determining the transmission signal quality. Based on the output characteristic principle of Mach-Zehnder electro-optic modulator, researches on its bias-point drifting for causing the reduction mechanism of modulation depth and extinction ratio are analyzed. Switching its internal state machine from FPGA is proposed to automatically adjust the bias voltage in real time realizing the operating bias-point control of Mach-Zehnder electro-optic modulator, which is studied through the theoretical investigation. A pulsed laser with the temperature sensing system of fiber Bragg grating ring-down cavity based on FPGA is established experimentally to demonstrate its effectiveness. The experimental results show the modulation depth and the extinction ratio of pulsed laser are improved by 40.45% and 32.85 dB, respectively. Output characteristic curve of the sensing system is optimized, which includes the phenomenon of initial curve rise of ring-down signals and the distortion of ring-down waveform are eliminated. The good linearity, repeatability, stability and accuracy of sensing system are investigated at the continuous variation temperature from −30℃ to 30℃.

Effect of dislocation and residual stress on etching performance of 12 μm thick rolled copper foil during pre-stretching

With the rapid development of new electronic information industry in 5G era, the development of various electronic components towards high speed and multi-functionality, and higher requirements have been put forward on the precision of circuit boards, the quality and rate of signal transmission. The 12 μm thick rolled copper foil is the thinnest rolled copper foil that can be stably produced, which is essential for the manufacture of high-end Flexible Printed Circuit (FPC) boards. The different microstructure and stress states of 12 μm thick rolled copper foil was obtained through different degrees of pre-stretching. And then the effect of dislocation and residual stress on the etching performance of copper foil was systematically investigated. The results show that the etching rate of copper foil increases and then decreases with the increasing of pre-stretching strain. And the etching rate of copper foil increases rapidly when the pre-stretching strain increases from 0.67% to 0.83%. For the dislocation, the rolled copper foil has higher dislocation density, and the dislocation density gradually increases with the increasing of pre-stretching strain. For the residual stress, the rolled copper foil has higher residual compressive stress. The residual compressive stress decreases and then turns into residual tensile stress with the increasing of pre-stretching strain. The residual compressive stress and dislocation reduce the etching rate of copper foil, and the residual tensile stress increases the etching rate of copper foil within a certain range. The four stages of etching rate variation of copper foil during pre-stretching were clarified, and the calculating model of etching rate was constructed when the dislocation density or residual stress acts as a single factor or dual factors.

Performance of Kramers–Kronig and coherent receivers in Medium-Reach optical communication

As the capacity and the transmission distance of medium-reach optical fiber communication systems continue to increase, it is a major trend in demanding lower optical link budgets while maintaining the quality of signal transmission. We experimentally compared the transmission performance of the Kramers–Kronig (KK) and the coherent receivers in a 20-Gbaud quadrature phase shift keying (QPSK) system over a ∼ thousand-kilometer standard single-mode fiber (SMF) link. Experimental results show that the KK receiver requires lower cost and simpler structure, and behaves similarly with the coherent receiver in the transmission under 1260 km, despite higher transmitted power and computational complexity.